This invention relates to a plotting head for use in a drawing machine, in particular a rectangular coordinates type drawing machine.
In the conventional rectangular coordinates type drawing machine, the plotting head has been constructed to have a rotary board mounted rotatably on a Y cursor and provided with a plurality of lead holders thereon, and has been so operated that when the lead received in one lead holder is used up, the rotary plate is rotated for locating another lead holder in a drawing position and the fresh lead received therein is used in succession.
The thus constructed plotting head is defective in that since the means for locating the rotary plate properly and the lead feeding means are respectively operated by different operating means, the mechanism is very complicated and additionally it is very difficult to locate the rotary board accurately.
Further, the conventional plotting head is defective in that since the lead holder can receive only a short lead of a length of about 60 mm at the most, a plurality of lead holders must be installed and consequently the line drawn with one lead accurately conforms, only with difficulty, to that drawn with another lead.